Tangul San

Connections between the facial, vestibular and cochlear nerve bundles within the internal auditory canal

The vestibular, cochlear and facial nerves have a common course in the internal auditory canal (IAC). In this study we investigated the average number of nerve fibres, the average cross‐sectional areas of the nerves and nerve fibres, and the apparent connections between the facial, cochlear and vestibular nerve bundles within the IAC, using light and scanning electron microscopy. The anatomical localization of the nerves within the IAC was not straightforward. The general course showed that the nerves rotated anticlockwise in the right ear from the inner ear end towards the brainstem end and vice versa for the left ear. The average number of fibres forming vestibular, cochlear, and facial nerves was not constant during their courses within the IAC. The superior and the inferior vestibular nerves showed an increase in the number of nerve fibres from the inner ear end towards the brainstem end of the IAC, whereas the facial and the cochlear nerves showed a reduction in the number of fibres. This suggests that some of the superior and inferior vestibular nerve bundles may receive fibres from the facial and/or cochlear nerves. Scanning electron microscopic evaluations showed superior vestibular–facial and inferior vestibular–cochlear connections within the IAC, but no facial–cochlear connections were observed. Connections between the nerves of the IAC can explain the unexpected vestibular disturbances in facial paralysis or persistence of tinnitus after cochlear neurectomy in intractable tinnitus cases. The present study offers morphometric and scanning electron microscopic data on the fibre connections of the nerves of the IAC.

Effect of extremely low frequency electromagnetic fields on growth rate and morphology of bacteria

Purpose: To determine the effect of extremely low frequency (<300 Hz) electromagnetic fields (ELF-EMF) on the growth rate of Gram-positive and Gram-negative bacteria and to determine any morphological changes that might have been caused by ELF-EMF. Materials and methods: Six bacterial strains, three Gram-negative and three Gram-positive were subjected to 50 Hz, 0.5 mT ELF-EMF for 6 h. To determine growth rate after ELF-EMF application, bacteria exposed to ELF-EMF for 3 h were collected, transferred to fresh medium and cultured without field application for another 4 h. Growth-rate was determined by optical density (OD) measurements made every hour. Morphological changes were determined with Transmission electron microscopy (TEM) for two gram-negative and two gram-positive strains collected after 3 h of field application. Results: A decrease in growth rate with respect to control samples was observed for all strains during ELF-EMF application. The decrease in growth-rate continued when exposed bacteria were cultured without field application. Significant ultrastructural changes were observed in all bacterial strains, which were seen to resemble the alterations caused by cationic peptides. Conclusion: This study shows that ELF-EMF induces a decrease in growth rate and morphological changes for both Gram-negative and Gram-positive bacteria.

Glutamate and GABA immunocytochemical electron microscopy in the hippocampal dentate gyrus of normal and genetic absence epilepsy rats

It is generally accepted that absence epilepsy results from the impairment of GABAergic and glutamatergic neurotransmission. In particular, besides excessive GABA mediation within the thalamo-cortico-thalamic circuit in absence epilepsy, neuronal networks of the hippocampus have recently received attention. In the present study, we examined the density of glutamate and GABA neurotransmitter immunolabeling in the dentate gyrus of the hippocampus of genetic absence epilepsy rats from Strasbourg (GAERS) compared to the control group. GABA and glutamate were found to exist in synaptic vesicles of the mossy fiber terminals of the control and GAERS groups. The density of glutamate immunolabeling within the mossy fiber terminals in the hilar region of GAERS hippocampus was found to be significantly decreased compared to the control group. There was no difference in the density of immunolabeling within GABA nerve terminals between GAERS and control group. The findings of this study suggest that mechanisms underlying absence seizures in GAERS may also manifest themselves in other brain regions such as the hippocampus. The presence of GABA within synaptic vesicles of mossy fiber terminals, as revealed by high resolution ultrastructural immunocytochemistry, has provided additional evidence to the possible modulatory role of GABA on synaptic transmission between the mossy fiber and the target cell.

Immunocytochemical analysis of glutamate and GABA in hippocampus of genetic absence epilepsy rats (GAERS).

In the present study, we used an immunocytochemical technique at the electron microscopic level to determine if there are changes in the glutamate and GABA neurotransmitter content of the hippocampus of genetic absence epilepsy rats from Strasbourg (GAERS). We also investigated if there was mossy fiber reorganization. After perfusion fixation, brains were removed and cryostat sections were stained according to the neo-Timms procedure. High-resolution electron microscopy was used for ultrastructural examination of the hippocampus of GAERS and non-epileptic control Wistar animals. For ultrastructural and immunocytochemical studies, ultrathin-cut sections were obtained and immunolabeled with anti-glutamate and anti-GABA antibodies. The number of gold particles per nerve terminal was counted and the area of the nerve terminal was determined using the program NIH Image Analysis. No mossy fiber sprouting was detected in the hippocampus of GAERS. GABA and glutamate immunoreactivity were observed in the mossy fiber terminals of both the control and GAERS groups. Glutamate density in the CA3 region of GAERS hippocampus was found to be significantly increased compared to the control group. However, there was no difference in the GABA density of nerve terminals and in areas of GABAergic and mossy terminals between GAERS and the control group. The difference in glutamate level may merely be due to strain differences between the GAERS strain and the original Wistar strain or it is also possible that it appears after seizures have started.

Evaluation of Hexagonal Boron Nitride as a New Tablet Lubricant

In this study, hexagonal boron nitride (HBN) was evaluated as a new lubricant for pharmaceutical tablet manufacturing. The other conventional lubricants such as magnesium stearate (MGST), stearic acid (STAC), and glyceryl behenate (COMP) were also tested along with HBN. Tablets were manufactured on an instrumented single-station tablet press to monitor and quantify the lower punch ejection force (LPEF). The force ratio, tablet crushing strength, disintegration time, and thickness were measured. The lubricant film formation and lubricant distribution in tablets were studied using the scanning electron microscopy (SEM) and electron probe micro analyzer (EPMA). Based on the force ratio, a good lubrication was obtained at 1% for MGST and HBN; in contrast, STAC and COMP did not show a good lubrication. After 1%, all lubricants performed well. MGST was found to be the most effective lubricant based on LPEF–lubricant concentration profile. HBN provided a 50% decrease in LPEF at 2% lubricant concentration and was rated as an effective tablet lubricant. HBN was better than either STAC or COMP. Unlike MGST, HBN had no significant prolongation effect on tablet disintegration times.

Collagen Ultrastructure and TGF-β1 Expression Preserved with Aminoguanidine During Wound Healing in Diabetic Rats

Advanced glycoxidation end products have been implicated in delayed diabetic wound healing. In this study, we evaluated the effects of aminoguanidine, which is an advanced glycation and nitric oxide (NO) synthase inhibitor, on extracellular matrix protein expression, collagen configuration, and nitrite/nitrate levels in wounds of diabetic rats. Sixteen Wistar male rats were made diabetic by streptozotocin. Of these, eight rats were given AG (aminoguanidine bicarbonate (AG) (group DAG) in their drinking water, and eight rats were followed as diabetic paired controls (group D). Eight healthy rats were followed as the healthy control group (group H). At the eighth week, a 2 × 2 cm area full-thickness skin defect was created. The degree of contraction of the open wounds was evaluated for 2 weeks duration. On the 15th postoperative day, wound surface areas were measured, and wound specimens and blood samples were collected. The shrinking percentage of the wounds was small in both groups H and DAG compared with group D (p < 0.05). Similar to healthy rats, the aminoguanidine-treated diabetic rats had very strong transforming growth factor (TGF)-β1 expression in granulation tissue and intact skin in comparison with diabetic controls. In the diabetic group, the intact skin demonstrated sparsely distributed regular collagen fibers in the granulation zone, and the regular pattern of collagen fibers was lost. In conclusion, aminoguanidine improves wound healing, restores growth factor TGF-β1 expression, and preserves collagen ultra structure, whereas it has no prominent effect on NO levels within wound tissue in diabetic rats.

Evaluation of Blood Cell Attachment on Er:Yag Laser Applied Root Surface Using Scanning Electron Microscopy

Background: Periodontal regeneration is dependent on the uninterrupted adhesion, maturation and absorption of fibrin clots to a periodontally compromised root surface. The modification of the root surface with different agents has been used for better fibrin clot formation and blood cell attachment. It is known that Er:YAG laser application on dentin removes the smear layer succesfully. Aim: The aim of this study is to observe blood cell attachment and fibrin network formation following ER:YAG laser irradiation on periodontally compromised root surfaces in comparison to chemical root conditioning techniques in vitro. Materials and methods: 40 dentin blocks prepared from freshly extracted periodontally compromised hopeless teeth. Specimens were divided in 5 groups; those applied with PBS, EDTA, Citric acid and Er:YAG. They were further divided into two groups: those which had received these applications, and the control group. The specimens were evaluated with scanning electron microscope and micrographs were taken. Smear layer and blood cell attachment scoring was performed. Results: In the Er:YAG laser applied group, smear layer were totally removed. In the blood applied specimens, better fibrin clot formation and blood cell attachment were observed in the Er:YAG group. In the group that had been applied with citric acid, the smear layer was also removed. The smear layer could not be fully removed in the EDTA group. Conclusion: Er:YAG laser application on the root dentin seems to form a suitable surface for fibrin clot formation and blood cell attachment. Further clinical studies to support these results are necessitated.

Time-dependent changes in distribution of basic fibroblast growth factor immunoreactive cells in rat hippocampus after status epilepticus

Abstract Objective: In this study, we aimed to examine time-dependent morphologic changes and quantitative alterations in the density of basic fibroblast growth factor (bFGF)-immunoreactive (ir) astrocytes and CA2 pyramidal neurons in dorsal hippocampus of rats after status epilepticus (SE) induced by kainic acid (KA) injection. Methods: Wistar albino rats were injected with saline or KA i.p. to investigate time-dependent alterations in morphology and the number of bFGF-ir astrocytes and neurons in the dorsal hippocampus 15, 30 and 90 days after KA injection. Results: Fifteen days after KA injection, gliosis was present throughout the hippocampus and neuronal loss was evident in CA1 and CA3 regions, which was more severe after 30 and 90 days. KA-injected rats demonstrated significantly increased number of both bFGF-ir astrocytes throughout the hippocampus and pyramidal neurons in CA2 after 15 days and decreased number after 30 and 90 days. Conclusion: The decrease in the number of bFGF-ir astroglia and neurons in long term after KA injection may indicate a decrease in the production of bFGF and/or number of bFGF-ir cells, suggesting that protective effects of bFGF might be altered during epileptogenesis in the hippocampus.

Morphological examination of the effects of defibrotide on experimentally induced bladder injury and its relation to interstitial cystitis

Abstract. This morphological study aims to investigate the effects of defibrotide, a deoxyribonucleic acid derivative drug with cytoprotective, immunosuppressive and vasorelaxant effects, on protamine sulfate induced bladder injury. Wistar albino female rats were catheterized and intravesically infused with phosphate buffered solution (control group) or, either protamine sulfate (bladder injury group) or protamine sulfate+defibrotide (bladder injury+defibrotide group) dissolved in phosphate buffered solution. The morphology of the urinary bladder was investigated using light and electron microscopy. The number of mast cells in the mucosa, mucosal alterations, intercellular junctions, surface topography and the glycosaminoglycan (GAG) layer as well as microvillus formation on the luminal surface were evaluated. In the bladder injury group, ulcerated areas, irregularity of the GAG layer, increased number of mast cells, vacuole formation, dilated perinuclear cistern, formation of pleomorphic and uniform microvilli and dilatations in the intercellular spaces in the urothelium were observed. In the bladder injury+defibrotide group a relatively normal urothelial topography, GAG layer and a few mast cells in the mucosa, some dilatations between the intercellular areas, less uniform microvilli, regular perinuclear cistern and tight junctions were observed. These results show that defibrotide can inhibit PS induced bladder damage.

Effect of aging on the distribution of basic fibroblast growth factor immunoreactive cells in the rat hippocampus

Hippocampal formation is extremely sensitive to the aging process and appears to be one of the first regions to show structural and physiological changes with advancing age. Basic fibroblast growth factor (bFGF) plays an important role in the stimulation of mitogenesis in glial cells, the support of neuronal survival and the promotion of neurite outgrowth in vitro. In the present study, the effect of aging on the distribution of bFGF immunoreactive (bFGF-ir) cells was investigated. The protein product of bFGF was visualized immunohistochemically in the dorsal hippocampus of Wistar albino rats. bFGF-ir astrocytes in different subfields of hippocampus and neurons in CA2 field were quantified to determine whether changes in immunoreactivity were correlated with advancing age. Aging was accompanied by a decrease in bFGF-ir cell density in subfields of hippocampus. We concluded that aging was associated with a reduction in bFGF-ir cell density that may reflect a decreased expression of bFGF in the rat hippocampus.